1. Field of the Invention
The present invention is directed to an apparatus for treating a subject with acoustic waves, of the type having an acoustic wave source which produces acoustic waves that are focused onto a therapeutic effective region, means for displacing the therapeutic effective region and the subject relative to each other, means for displaying an image of a body region of the subject which is to be treated with the focused acoustic waves, and means for mixing a mark which indicates the position of the therapeutic effective region into the displayed image.
2. Description of the Prior Art
Apparatuses of this sort are known for example from European Application 0 148 653 and from the book Biliary Lithotripsy (eds. J. T. Ferrucci et al.), Adapted from the Proceedings of the First International Symposium on Biliary Lithotripsy, Jul. 11-13, 1988, pages 253-263, 263a; B. Forssmann et al.: "Dornier: MPL 9000 Multipurpose Lithotripter." In this apparatus, focused ultrasound waves are produced as acoustic waves. One or several ultrasound tomograms of the body region to be treated containing the focus of the ultrasound waves, obtained by means of an ultrasound location apparatus, are displayed. In the case of European Application 0 148 653, an ultrasound transducer is provided for this purpose, connected with the source in such a way that the imaged body region contains the therapeutic effective region of the ultrasound waves. In the case of the MPL 9000 Multipurpose Lithotripter, another adjustable ultrasound transducer is additionally provided, by means of which a second body slice containing the body region to be treated can be displayed.
In order to treat a particular body region, in the known apparatus the source, including the ultrasound transducer of the ultrasound location apparatus, is first displaced relative to the body of the subject to be treated until the body region to be treated is imaged in the ultrasound tomogram, and the mark coincides with the body region to be treated. The charging of the region to be treated with the focused ultrasound waves then takes place.
The known apparatus can be used only conditionally, in cases in which the body region to be treated differs sufficiently from the structures surrounding it with respect to its acoustic characteristics to enable a sufficiently clear representation in an ultrasound tomogram.
In order to provide aid here, in the case of an apparatus known from EP 0 534 607 A1 a magnetic resonance (MR) diagnostic apparatus is provided as a location apparatus. Though nothing is then left to be desired even during the treatment with respect to the image quality of the image information provided, particularly in the representation of tumors, it is however extremely expensive to use an MR diagnostic apparatus as a location apparatus, since this apparatus is not available for other purposes while a treatment is being carried out. Moreover, the patient is accessible by the medical personnel only with difficulty, due to the presence of magnets and radio-frequency coils.